I think you'll miss the tide on this one, arguably the ice bucket thing has already peaked. But keep that code handy! you'll be able to adapt it next viral video craze with ease
It would be nice to have a graph of challenger-challengee relations. However, I just tried to trace back two challenges and all traces fizzled out in dead ends (no names/private persons) after a couple of hops.
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On a different note, it generally strikes me as extremely disproportional how much attention this ALS gets dues to the Ice Bucket Challenge. It is a horrible disease, but awareness in other areas is much more urgently needed, such as in AI security research, asteroid impact avoidance, world peace, climate change, resource scarcity and for basic income pilot projects etc. It's depressing that society as a whole is so bad a coordinating priorities.